Improvement in machines for cutting screw-threads on



SALMON W. PUTNAM. Jn., or erroneous, MAssAoHUsn'rfs.

Letters Patent No. 111,248, dated January 24, 1871.

IMPRQVEMENT IN MACHINESFOR CUTTING SCREW-THREADS ON BOLTS.l

The Schedule referred to in these Letters Patent and making part of me same.

To ai? 'whom lit may concern;

,Be it. known that `I,' SALMON W. PUTNAM, Jr., of Fitchburg, Worcester county, .State of Massachusetts, have invented certain new and useful Improvements in Screw-bolt Threading-Machines; and I do hereby declare that the following, taken in connection witlrthe drawing which accompanies and forms part ot' this speeiiicat-i'on, is a description of my invention'suficient to enable those skilled in the art to practice it.

rEllis invention relates, to details in the construction of that class of machines in which the bolt to be screwthreaded is held from rotation, but is allowed 'to advance toward and retreat from the screw-thread-ibrming dies which are v*made to rotate.

The drawing shows'of my improved Figure 1, a side view; in` 'l Figure?, a vertical central longitudinal section; in

Figure 3, a front-end View with the front cap a removed; in f Figure 4, a plan; and in Figure 5, a plan ofthe portion of the front end of the hollow rotating spindle which carries theY screwthread-cutting dies.

'ct is the head or standard, in which is formed a pipebox, which receives a hollow arbor, b, to the rear of which is attached thewh`eel or pulley, which, by a belt or other suitable means, causes rotation of the arbor.- y

On the arbor, at the front of the head a, is fixed a collar, c, to which, by means of `a screw, tl, passing through a slotted hole in-the collar, is adjustably attached a sleeve, e, which is so iitted on the arbor b rthatit can be `turned thereon, when the clamp-screw l is loosened, by application of a lever or wrench in the holes madeat the rear of e for that purpose.

011 the front end of the arbor Zr is iitted, so as to turn freely thereon, a ring, f, on the peri pheryof which are formed two grooves, one of which is seen most clearly in iig. 5, each of said grooves beinginclinedto the axis of arbor b, except for a short distance from lthe filent of the ring, where the grooves are made parallel with said axis.

Into the material of ring f are cut cam-grooves, seen in ne. 3 and marked g, the purpose of whichis to receive projections on the dies It, which fit in slots madein the iront end of arbor b, so that, by turning ring h, the dies can bc forced toward and drawn from the center ofthe arbor.

To. impart a turning motiontc the ring f a sliding cylindrical piece, 'i, is splined to the sleeve e, so that it calnslide freely thereon without turning, said piece 'i having iixcd to it pins or rolls which lit in the grooves before 'mentioned in the periphery of ring f, 'which grooves are markcdj.

machine, iu#- In the rear of piece t `ismad-e a groove concentric with the arbor b, in which groove is titted, in l -cither forces thedies' toward the center of rotation of arbor b or withdraws them from it, according as the lever 7J is vibruted toward or from the front end of the arbor b.

In the ring f,communicating with the cam-grooves g therein, are'cut openings, on, through the periphery of f, 'the purpose of which is to allow the extraction of the dies without removing the ringed cap-piece n, which is secured to the face of'arbor la, and holds the dies in the grooves h formed therein, and prevents access of foreign matter to the dies.

Inthe ring part of n are cut slots, which correspond in location to the position of the openingsfm in ring f, and said slots arc closed to prevent foreign mattei' from getting into and clogging the action of the incased parts.

The closing of the slots may be elfect'ed, as shown, by slides c, or an external ring may be applied whichl may be removed, or, if it is also slottedkitmay be turned upon 'i to open or close the slots therein.`

Figure 6 shows `one of the screw-thread-cutting dies in edge and side elevations.

lhese dies are made in sets to suit, within reasonablc limits, any diameter of bolt, the operative ends being shaped to produce threads of desired form, pitch, and spacing.

'l'he arbor b being tubular its internal diameter is the limit of the diameter ot' the bolts which can be screw-threaded in the machine, while the length over which the screw-threads can bc cut is only limited by the length of thc rods or bolts introduced .into the` machine for its action.

In operating to cut screw-threads, the diesA being rightly adjusted and the arbor in rotation, the attendant draws forward the lever 7a, and presents the bolt to the dies, which seize upon it and draw between the dies into the hollow arboras the dies cut the threads thereupon.

NVhen'the screw-threads have been cut upon a suf-` ent' more or less deeply on the rod presented to them,

and thus within reasonable limits the diameters of the screw-threaded parts may be varied.

f To aid the operator in setting the dies to any given diameter' adjacent 'index-scales are marked on the sleeve e and on the collar c.

When one set of dies is to be removed and another set substituted the openings in the cap-u are uncovered and thebolt el is slackencd, so that, by turning the sleeve e relatively to the collar c, the opcningswn are brought into line withj the die-liolding grooves in the face of the arbor b, and then by turning slowly the arbor b the dies will drop out one after the other and their places can be supplied with another set,

which are adjusted in position by turning sleeve c relatively to the collar c.

To indicate to the operator when a screw-thread has been out over any desired length of bolt, I make an attachment tothe machine, as follows:

Within the bore of arbor b Iv place a piston or disk,`

j), to which is attached a rod, q, extending through arbor b, and beyond its rear, where it is screwed into one end of a bar, r, which extends in any convenient direction to a location in view of the operator, where it can be fitted as a guided slide carrying an indexinger, s, extending to the divisions of a scale or rnle.

It will be obvious that as the bolt or rod which the inachineis operating on to screw-thread4 passes through the dies it will force piston p rearward to a distance indicated by the' index s, so that when any desired length of the rod has received the action ofthe dies they are thrown open clear of the rod by the operator.

To bring back the disk 1) to its position against the dies I make use of any sirnplc attachment ot' a weight or spring to the bar/r, the arrangement of the weight indicated in the drawing being suicient for the purpose. l

Ihe disk p may be nicely adjusted with reference to of bar fr, and, when adjusted, kept in position by screwing a check-nut against said end.

This apparatus may detached from the machine in whole or in part when it is desired to' cut very long screws. e l

When the rollsor pins attached .to the piece 'i are in those parts of grooves j which are parallel with the axis of the arbor b, the ring f is locked thereby, as the strain of the dies h will not then tend to force the piece t backward, as would be the case it' the grooves j were inclined to the axis of rotation tl'iroughout their entire length.

I claiml. J ointly, the ring f, constructed as described, with the double-acting cam-grooves in its end or front face,

and the spiral or inclined grooves on its periphery, terminating toward the front end in the short straight grooves, and the combination of the said ring with the hollow arbor I), the cylindrical piece t', provided on its inner surface with rolls or pins, vand the lever lg., all as shown and described.

2. The cap a, made to `liold thc dies in the grooves, and constructed with covered openings to be used in conjunction with the openings m, substantially as described.

3. bor, of thcdisk 1)loeat-ed within the arbor, and connected with an indicator, and so arranged that the amount of its movement, caused by passage of a bolt through the dies, may beindicatcd to the operator, substantially as and for the purpose set forth.

l SALMON \V. PUTNAM, JP..

Witnesses C. F. PUTNAM, JonN F. HA-sKrNs.

The combination, with a hollow die-carrying ar- 

